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- Y. Otake, K. Tamasaku
RIKEN Spring-8 Harima, Hyogo
- N. Hosoda, M. K. Kitamura, H. Maesaka, T. Ohshima
RIKEN/SPring-8, Hyogo
- K. Imai, M. Kourogi
OPtical Comb, Inc., Yokohama
- M. Musya
University of electro-communications, Tokyo
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At RIKEN, a coherent X ray source is under construction. Timing and rf phase accuracy of several femto-seconds is required to the timing and LLRF system for an XFEL accelerator. We already realized an electron beam timing stability of 46fs (rms) with electronic circuits in the SCSS test accelerator. However, realizing the required timing accuracy is more 10 times difficult than that achieved with the electronic circuits. We try to obtain this accuracy by a laser system. This system comprises 4 parts;- an optical comb generator, having 5712 MHz, 1 ps width pulse train, as which has LN crystal installed into an optical Fabry-Perot cavity,
- a DFB laser locked to an acetylene absorption spectrum (1538 nm),
- an optical fiber length regulation system, which has a control function of its thermal length change reduced within 25um for 25km by a Michelson interferometer, and
- a WDM optical system to transmit timing and rf signals, such as 5712 MHz and 238 MHz for the acceleration.
In this paper, we describe the system configuration, and the results of the developed laser instruments. The instruments noise of less than -100 dBc showed great possibility to realize the requirement.
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